Search

Background Reoccurring Ebola outbreaks in West and Central Africa have led to serious illness and death in thousands of adults and children. The objective of this study was to assess safety, tolerability, and immunogenicity of the heterologous 2-dose Ad26.ZEBOV, MVA-BN-Filo vaccination regimen in adolescents and children in Africa. Methods and findings In this multicentre, randomised, observer-blind, placebo-controlled Phase II study, 131 adolescents (12 to 17 years old) and 132 children (4 to 11 years old) were enrolled from Eastern and Western Africa and randomised 5:1 to receive study vaccines or placebo. Vaccine groups received intramuscular injections of Ad26.ZEBOV (5 × 1010 viral particles) and MVA-BN-Filo (1 × 108 infectious units) 28 or 56 days apart; placebo recipients received saline. Primary outcomes were safety and tolerability. Solicited adverse events (AEs) were recorded until 7 days after each vaccination and serious AEs (SAEs) throughout the study. Secondary and exploratory outcomes were humoral immune responses (binding and neutralising Ebola virus [EBOV] glycoprotein [GP]-specific antibodies), up to 1 year after the first dose. Enrolment began on February 26, 2016, and the date of last participant last visit was November 28, 2018. Of the 263 participants enrolled, 217 (109 adolescents, 108 children) received the 2-dose regimen, and 43 (20 adolescents, 23 children) received 2 placebo doses. Median age was 14.0 (range 11 to 17) and 7.0 (range 4 to 11) years for adolescents and children, respectively. Fifty-four percent of the adolescents and 51% of the children were male. All participants were Africans, and, although there was a slight male preponderance overall, the groups were well balanced. No vaccine-related SAEs were reported; solicited AEs were mostly mild/moderate. Twenty-one days post-MVA-BN-Filo vaccination, binding antibody responses against EBOV GP were observed in 100% of vaccinees (106 adolescents, 104 children). Geometric mean concentrations tended to be higher after the 56-day interval (adolescents 13,532 ELISA units [EU]/mL, children 17,388 EU/mL) than the 28-day interval (adolescents 6,993 EU/mL, children 8,007 EU/mL). Humoral responses persisted at least up to Day 365. A limitation of the study is that the follow-up period was limited to 365 days for the majority of the participants, and so it was not possible to determine whether immune responses persisted beyond this time period. Additionally, formal statistical comparisons were not preplanned but were only performed post hoc. Conclusions The heterologous 2-dose vaccination was well tolerated in African adolescents and children with no vaccine-related SAEs. All vaccinees displayed anti-EBOV GP antibodies after the 2-dose regimen, with higher responses in the 56-day interval groups. The frequency of pyrexia after vaccine or placebo was higher in children than in adolescents. These data supported the prophylactic indication against EBOV disease in a paediatric population, as licenced in the EU. Trial registration ClinicalTrials.govNCT02564523. Zacchaeus Anywaine and co-workers study safety and immunogenicity of an Ebola vaccine among children and adolescents across four African countries. Author summary Why was the study done? There have been larger and more extensive Ebola virus disease (EVD) outbreaks in Africa in the past decade with no licenced treatments available. As such, there is an unmet medical need for prophylactic Ebola vaccines. This study was performed to evaluate whether a 2-dose heterologous Ad26.ZEBOV, MVA-BN-Filo Ebola vaccination was safe and immunogenic in healthy African children. What did the researchers do and find? In this randomised, placebo-controlled, Phase II clinical trial, the Ad26.ZEBOV, MVA-BN-Filo Ebola vaccination regimen was administered to African participants in 2 age cohorts (12 to 17 and 4 to 11 years). No vaccine-related serious adverse events were reported, and robust immune responses were induced in both adolescents and children after receiving the active 2-dose regimen. What do these findings mean? These data support the use of the Ad26.ZEBOV, MVA-BN-Filo vaccination regimen in African adolescents and children at risk of Ebola infection. Although vaccination according to a 28-day regimen may lead to protection against EVD in a shorter time frame, vaccination according to a 56-day regimen results in higher EBOV GP binding and neutralising antibody responses. The observation that Ad26 preexisting immunity in the majority of participants does not affect the EBOV GP-specific antibody responses postvaccination augurs well for the use of this vaccine regimen even in regions with a high prevalence of preexisting Ad26 seropositivity.

Background We investigated safety, tolerability, and immunogenicity of the heterologous 2-dose Ebola vaccination regimen in healthy and HIV-infected adults with different intervals between Ebola vaccinations. Methods and findings In this randomised, observer-blind, placebo-controlled Phase II trial, 668 healthy 18- to 70-year-olds and 142 HIV-infected 18- to 50-year-olds were enrolled from 1 site in Kenya and 2 sites each in Burkina Faso, Cote d’Ivoire, and Uganda. Participants received intramuscular Ad26.ZEBOV followed by MVA-BN-Filo at 28-, 56-, or 84-day intervals, or saline. Females represented 31.4% of the healthy adult cohort in contrast to 69.7% of the HIV-infected cohort. A subset of healthy adults received booster vaccination with Ad26.ZEBOV or saline at Day 365. Following vaccinations, adverse events (AEs) were collected until 42 days post last vaccination and serious AEs (SAEs) were recorded from signing of the ICF until the end of the study. The primary endpoint was safety, and the secondary endpoint was immunogenicity. Anti-Ebola virus glycoprotein (EBOV GP) binding and neutralising antibodies were measured at baseline and at predefined time points throughout the study. The first participant was enrolled on 9 November 2015, and the date of last participant’s last visit was 12 February 2019. No vaccine-related SAEs and mainly mild-to-moderate AEs were observed among the participants. The most frequent solicited AEs were injection-site pain (local), and fatigue, headache, and myalgia (systemic), respectively. Twenty-one days post-MVA-BN-Filo vaccination, geometric mean concentrations (GMCs) with 95% confidence intervals (CIs) of EBOV GP binding antibodies in healthy adults in 28-, 56-, and 84-day interval groups were 3,085 EU/mL (2,648 to 3,594), 7,518 EU/mL (6,468 to 8,740), and 7,300 EU/mL (5,116 to 10,417), respectively. In HIV-infected adults in 28- and 56-day interval groups, GMCs were 4,207 EU/mL (3,233 to 5,474) and 5,283 EU/mL (4,094 to 6,817), respectively. Antibody responses were observed until Day 365. Ad26.ZEBOV booster vaccination after 1 year induced an anamnestic response. Study limitations include that some healthy adult participants either did not receive dose 2 or received dose 2 outside of their protocol-defined interval and that the follow-up period was limited to 365 days for most participants. Conclusions Ad26.ZEBOV, MVA-BN-Filo vaccination was well tolerated and immunogenic in healthy and HIV-infected African adults. Increasing the interval between vaccinations from 28 to 56 days improved the magnitude of humoral immune responses. Antibody levels persisted to at least 1 year, and Ad26.ZEBOV booster vaccination demonstrated the presence of vaccination-induced immune memory. These data supported the approval by the European Union for prophylaxis against EBOV disease in adults and children ≥1 year of age. Trial registration ClinicalTrials.govNCT02564523 Houreratou Barry and co-workers report on safety and immunogenicity of an Ebola vaccine in adults across four African countries. Author summary Why was this study done? With Ebola outbreaks increasing, there is an unmet medical need for a prophylactic vaccine to prevent and mitigate Ebola outbreaks. To address the urgent medical need during the 2014 to 2016 outbreak, the clinical development of the 2-dose vaccine regimen comprising of Ad26.ZEBOV and MVA-BN-Filo was accelerated. This Phase II study was part of this accelerated program, evaluating the safety and immunogenicity of the 2-dose vaccine regimen in healthy and HIV-infected African adults, with 28-, 56-, and 84-day intervals between doses. The study was amended to evaluate safety and immunogenicity of a booster vaccination with Ad26.ZEBOV, administered approximately 1 year after the first vaccination, in healthy adults. What did the researchers do and find? We conducted a randomised trial to assess the safety and the immunogenicity of the Ad26.ZEBOV, MVA-BN-Filo vaccine regimen in 3 different vaccination intervals in healthy and HIV-infected adults. The vaccine regimen was well tolerated and induced marked immune responses; the highest humoral responses were observed after vaccination with 56-day and 84-day intervals. Anamnestic responses were observed in all healthy participants receiving Ad26.ZEBOV as booster at 1 year after the first dose. What do these findings mean? Our results demonstrate that the Ad26.ZEBOV, MVA-BN-Filo vaccine regimen is safe and immunogenic in healthy and HIV-infected adults and induces immune memory that can rapidly be reactivated. Our findings support the prophylactic use of the 2-dose Ad26.ZEBOV, MVA-BN-Filo vaccine regimen against Ebola infection in African adult populations. The 2-dose vaccine regimen comprising of Ad26.ZEBOV and MVA-BN-Filo has received marketing authorisation under exceptional circumstances for prophylactic use against EVD in adults and children ≥1 year old within the European Union.